I can't find this key:
W: GPG error: http://ftp.us.debian.org sid Release: The following
signatures couldn't be verified because the public key is not available:
NO_PUBKEY AED4B06F473041FA
Any pointers?
-ishwar

You can try that with the last 8 numbers of the PUBkey
gpg --keyserver subkeys.pgp.net --recv-keys 473041FA